Project Summary ? Project 2 Reversing the epigenetic code of aging through ketogenic diets The epigenetic modifications that cause aging and tissue degeneration are currently unknown. We measured the methylated lysines of histone H3 in mouse livers with aging to identify the epigenetic signature of aging. Caloric restriction (CR) intervention, which extends lifespan, preserved a younger epigenetic profile, reversing multiple epigenetic marks. We plan to overlap the epigenetic signature of aging with ketogenic diet (KD) and CR interventions, with metabolomic profiles and transcriptomic profiles prepared by Project 2. This will result in a product of aging-responsive and KD-responsive and metabolically mapped epigenetic biomarkers that reverse the epigenetic signature of aging. The hypothesis of Project 2 is that epigenetic marks drive the program of aging and cognitive decline, and that determining the epigenetic signature of the KD will point out genes and metabolic nodes that can serve as biomarkers of the KD functional effect to extend functional longevity. A further hypothesis is that these biomarkers identified in mice could overlap those in humans, thereby pointing to human biomarkers of aging as well as dietary amelioration. The goal of this study is to determine the epigenetic effects of KD on aging and neurodegeneration. Specific Aims include the following: 1) identify the epigenetic profile of aging through assessment of histone marks; 2) dissect the interaction between diets and chromatin regulation during aging by overlapping metabolomics, transcriptomics and epigenomics; and 3) overlap the mouse epigenetic signature of aging with humans to the extent possible to identify age- related biomarkers. To achieve these aims, Project 2 will determine the histone code of aging in wild-type and Alzheimer's model mice. We will overlap age- and diet-related epigenetic, transcriptomic and metabolomic profiles and biomarkers, together with Project 1 and Core B, to identify functional biomarkers of aging and cognitive decline that are reversed by the KD. We will also investigate the epigenetic signature of potential biomarkers in the blood of aged individuals, and in Alzheimer's brain tissue chunks provided by Core C. Project 2 has the potential to identify functional biomarkers of aging and cognitive decline, and to identify which of these biomarkers respond to the KD in mice. Because the same biomarkers can be tested in human samples, there is the potential to identify novel human biomarkers of functional aging and how to reverse them through dietary strategies.